Recent advances of various kinds of imaging diagnosis technologies have made it possible to diagnose and treat hepatocellular carcinoma at earlier stages. However, in a treatment of hepatocellular carcinoma, frequency of conducting a hepatectomy is often limited for fear of occurrences of complication of cirrhosis and multifocal involvement. For this reason, a number of non-surgery local treatments such as percutaneous ethanol infusion, hepatic arterial embolization, chemical therapy and radiation therapy have been attempted because of their small influence on the hepatic function and easiness of treatment in the case of recurrence, in comparison with hepatectomy.
In order to securely necrose hepatocellular carcinoma, a radiofrequency ablation (hereinafter, referred to as RFA) using a radiofrequency wave (460±5 kHz) has been made into practical use. This therapy ablates cancer cells by causing a tissue to automatically generate frictional heat in response to dielectric heating (see, Syuichiro Shina et al., “Percutaneous radiofrequency ablation”, Japanese Journal of Cancer Clinics, Vol. 47, No. 11, p 1081-1088, November 2001; and Masatoshi Kudo, “Local treatment of cancer cells”, Journal of Clinical and Experimental Medicine, Vol. 200, No. 10, p809-811, Mar. 9, 2001).
Also, a percutaneous microwave coagulation therapy (hereinafter, referred to as PMCT) has been developed and made into practical use. This method coagulates tumors using a microwave (2450±50 MHz) which is an electromagnetic wave. This method utilizes frictional heat generated by dielectric heating to coagulate tumor tissues. However, the RFA is more frequently used than the PMCT because it leads less complications than the PMCT.
In the RFA, it is often the case that ablation is conducted several times because a sufficient ablation area is not achieved by a single operation. The RFA also has the problems that an ablation area has unevenness because heat is not transferred evenly due to cooling by the blood circulation, and that the incidence of recurrence of cancer largely differs in different facilities.
It is an object of the present invention to provide an adjuvant capable of extending an ablation area and reducing unevenness of ablation mainly in a RFA-assisted ablation of a lesion site.